Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.

The most accurate timepiece in the world.

This historic roadhouse has many tales to tell of San Francisco's early history.

Forgotten and then destroyed by fire, this was once one of the largest saltwater swimming pools in the world.

Gold Rush-era tombstones line the park's paths.

This eatery transports diners to a place that no longer exists: East Germany.

Join the circus for a few lessons to learn clowning, acrobatics, and Chinese contortion.

This grinning pup statue is all that's left of what was once a ubiquitous Bay Area diner chain.

An artsy hidden staircase leads to breathtaking views of San Francisco.

The oldest burial ground in the city, final resting place of city founders, Ohlone natives and murderers alike.

This one-block alleyway is stuffed with street art that is colorful, cultural, and intensely political.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

The miraculous hydrant that saved the Mission District in 1906.

A shop full of natural curiosities, carnivorous plants, and costumed taxidermied mice.

An essential stop before plundering, BYO Cutlass.

Overflowing with shipping containers, this location has been transformed into a massive workspace for artists.

A 140-year-old castle with underground caves hidden in San Francisco.

A tribute to the artist and activist who created the rainbow pride flag.

Radioactivity still cause for concern at this urban explorer's paradise.

Adolph Sutro's little-known, geographically inaccurate, deprecated monument.

A bronze tribute to a legendary Californian, the self-proclaimed "Emperor of the United States."

This colorful boulder serves as a canvas for political statements and artistic expression.